How can I revive an OLD sourdough starter that’s been hibernating in the fridge?

As long as your sourdough starter is alive, all you have to do is take it out of the fridge, wait for it to thaw and come to room temperature, and then you just discard a little bit and then feed it and then just wait and see for any kind of activity

I don’t think it’s dead, so just feed your sourdough starter and then wait for it to double in size.

Your sourdough starter should go up and down, up and down consistently.

It may take two or three feedings, but I think it’s still alive so long as you don’t see any signs of pink, orange, green, black, gray or fuzz.